Keratome with suspended stabilized blade, improved suction ring with applanator and guided engagement with keratome cutter head, automated translation of the cutter head, and blade insertion tool

ABSTRACT

A keratome includes a cutting instrument having a cutter head with a reciprocating blade and a cutting edge extending below a sole surface of the cutter head, an automated drive unit mounting the cutting instrument for powered translational movement of at least the cutter head thereof, and a suction ring including an eye ring adapted to be secured to an eye by suction and defining a cornea aperture for presenting the outer layer of the cornea of the eye for cutting. The suction ring has a shoe from which the eye ring extends, the shoe defining a cutting guideway configured for receiving the cutter head in precision mating sliding engagement when the cutting edge of the blade is positioned over the cornea aperture of the eye ring, and an entrance guideway extending from and generally aligned with the cutting guideway, the entrance guideway configured for receiving the cutter head in orienting sliding engagement and positively positioning the cutter head for precision mating sliding engagement with the cutting guideway.  
     The automated drive unit and the suction ring are configured for releasable attachment when said cutter head is received in the entrance guideway of the suction ring.  
     The automated drive unit is operable to slidingly translate the cutter head into the cutting guideway and to withdraw the cutter head therefrom.

[0001] This application is division of application Ser. No. 09/434,838filed May 4, 1999, now U.S. Pat. No. ______ which was acontinuation-in-part of application Ser. No. 09/178,282 filed Oct. 23,1998 which claimed priority to Provisional Application Serial No.60/063,083 filed Oct. 24, 1997, and also claimed priority to ProvisionalApplication 60/107,197 filed Nov. 5, 1998.

FIELD OF THE INVENTION

[0002] The invention herein relates to a keratome having a cutter headwith a suspended stabilized reciprocating blade, an improved suctionring accepting an applanator and with entrance and cutting guideways forpresenting and applying the cutter head and its suspended blade to thecornea, drive means for automated translation of the cutter head, andblade insertion cooperating with the cutter head.

BACKGROUND OF THE INVENTION

[0003] A keratome is an instrument used in ophthalmic surgery and, moreimportantly, in surgery to reshape the cornea for vision correction. Akeratome incises a generally spherical segment of the cornea except fora connecting hinge. The cornea segment is lifted and held aside whilethe exposed truncated cornea surface is shaped for vision correction.Thereafter, the spherical cornea segment is repositioned to cover theshaped, truncated cornea surface. The cornea segment heals to the shapedsurface, resulting in a reshaped cornea that acts as a corrective lens.

[0004] It will be appreciated that a keratome must achieve an accuratelypositioned, surgically precise cut with minimal tissue damage to enhancethe healing process. Further, the cut must remain uncontaminated, alsoto aid the healing process and avoid irritation and infection.

[0005] In accurately positioning and performing a cornea cut, it isknown to use a suction ring as an interface with the eye. Suction isused to temporarily secure the suction ring to the eye in a desiredposition. Typically, a suction ring is secured to the sclera, near theperiphery of and surrounding the cornea.

[0006] It is also desirable to measure the cornea and coordinate theextent of the incision with the size of cornea in order to remove aproperly sized cornea segment and to provide an appropriate hinge inconjunction with the excised cornea segment.

[0007] It is also known to apply a cutting instrument with the suctionring. Thus, the suction ring positions and presents the cuttinginstrument with respect to the cornea. Clearly, if any slippage ordisengagement of the suction ring occurs, a correspondingly inaccuratecut may also occur. Present suction rings occasionally do experienceslippage or disengagement, and it is believed this occurs because of apoor interface with the surface of the sclera resulting in loss ofsuction or uneven suction along various segments of the ring. Currently,engagement of a cutting instrument with a suction ring is oftendifficult to achieve, because the engagement must be precise, making theengagement difficult to initiate.

[0008] Precision of the cornea cut requires proper positioning of acutting instrument with respect to the cornea, which is achieved by thelocation and secure attachment of the suction ring, and also requires avery smooth operating cutting blade. Cutting instruments often use areciprocating cutting blade to achieve a smooth, precise incision. Anyflutter in the operation of the reciprocating cutting blade can cause asomewhat ragged incision, with consequent difficulties in replacing thecornea segment and smooth healing thereof.

[0009] The cornea cut must also remain uncontaminated, because anyforeign matter in the incision may become encapsulated and causeirritation and possible infection. Cutting instrument designs whichsupport a cutting blade on a bearing surface adjacent the area of theincision increase the risk of contamination. Contact between the cuttingblade and the bearing surface creates friction and wear. This not onlyheats the cutting blade, but also sloughs off microscopic metal wearparticles. These may lodge in the cornea incision, with undesirableeffect.

[0010] It is also desirable to translate the cutting instrument acrossthe cornea in a smooth manner and to reliably stop the translation ofthe cutting instrument at the furthest extent of the cut. Non-damagingwithdrawal of cutting instrument is also desirable.

[0011] There is also a need to quickly and easily load blades into thecutting instrument, and to remove blades after use.

[0012] Therefore, there is a need for a keratome including a suctionring that easily, accurately and securely positions a cutting instrumentwith respect to the cornea and that provides a surgically precise,uncontaminated incision of a cornea segment. There is an additional needfor improved automation in making the incision.

SUMMARY OF THE INVENTION

[0013] Accordingly, it is a principal object of the invention herein toprovide a keratome for ophthalmic surgery.

[0014] It is an additional object of the invention herein to provide akeratome that achieves accurate and secure engagement with the eye.

[0015] It is another object of the invention to provide a keratome thatfacilitates accurate, pre-cut measurement of the cornea.

[0016] It is also an object of the invention to provide a keratomeincluding a cutting instrument that is easily and accurately engageablewith a suction ring secured to the eye.

[0017] It is an additional object of the invention to provide a keratomewith automated translation of a cutting instrument across a suctionring.

[0018] It is a further object of the invention to provide a keratomethat achieves an accurate and smooth cut.

[0019] It is another object of the invention to provide a keratome thatavoids contamination of the incision made on the cornea.

[0020] It is also an object of the invention to provide a keratome withsimple and efficient changing of the blade in a cutting instrument.

[0021] According to general aspects of the invention herein, a keratomegenerally comprises a suction ring and a cutting instrument having acutter head guided into precision sliding engagement with the suctionring, the cutter head including a suspended, reciprocating blade. Anapplanator is receivable on the suction ring for measuring the segmentof cornea to be cut, and the cutting instrument is adjustable or presetfor length of cut.

[0022] Also according to aspects of the invention, a keratome generallycomprises a cutting instrument having a cutter head including areciprocating blade with a cutting edge extending below a sole surface,and a suction ring. The suction ring includes an eye ring adapted to besecured to an eye by suction and defines a cornea aperture presentingthe cornea of the eye for cutting a cornea segment. The suction ringfurthers includes a shoe from which the eye ring extends, the shoedefining a cutting guideway configured for receiving the cutter head inprecision mating sliding engagement for passing the cutting edge of thecutter blade over the cornea aperture and thereby incising a corneasegment. The shoe further defines an entrance guideway extending fromand generally aligned with the cutting guideway, the entrance guidewayconfigured for receiving the cutter head in orienting sliding engagementpositively positioning the cutter head into the aforesaid precisionmating sliding engagement in the cutting guideway.

[0023] According to additional aspects, the cutter head defines twotongues extending downwardly at the edges of its sole surface, and thecutting guideway includes two guide grooves respectively receiving thetongues. The cutting guideway guide grooves are fully defined at thetransition between the entrance guideway and the cutting guideway.According to further aspects, the entrance guideway is partially definedby a guide hoop of the shoe, and the cutter head is cooperatively shapedto enter the guide hoop and progressively orient the cutter head forentry to the cutting guideway. The guide hoop is preferably positionedsubstantially at the transition between the entry guideway and thecutting guideway. Also, according to further aspects, the entranceguideway includes curbs upstanding along the marginal edges of anentrance ramp portion of the shoe for generally aligning the cutter headwith the guide hoop, the shoe defines side rails extending from theguide hoop, and the cutter head has side rail pockets slidinglyreceiving the side rails. Thus, there are multiple points of contactbetween the cutter head and the shoe defining the entrance guideway,serving to align the cutter head for sliding movement in the cuttingguideway. The foregoing configurations of the cutter head and suctionring provide easy engagement and accurate positioning of the cutter headwithin the suction ring.

[0024] Referring to another aspect, the suction ring includes a handleand the handle is preferably positioned opposite the entrance guidewayof the suction ring, for manual stabilization of the suction ring andcoordination of the suction ring and cutting instrument duringintroduction of the cutting instrument.

[0025] According to still other aspects in the invention, a suction ringincludes an eye ring defining a cornea aperture and a shoe, and the shoedefines a socket for receiving and positioning an applanator with ameasuring surface in contact with a cornea of an eye presented throughthe cornea aperture, for measuring the size of the cornea to be incised.Cooperating stop means are provided between the suction ring and cuttinginstrument for adjusting the extent of the incision according to theapplanator measurement of the cornea.

[0026] According to a still further aspect of the invention, the cuttinginstrument includes a stop which butts against the suction ring at adesired extent of incision. The stop is preferable a rotatable collaradjustably presenting one of a plurality stops for selectively settingdifferent extents of incision.

[0027] According to additional aspects, a suction ring includes an eyering with outer and inner contact surfaces shaped to engage the eye, anda suction channel defined between the inner and outer contact surfaces.The suction channel additionally defines a secondary distributionchannel and a suction conduit opens to the suction channel and thesecondary distribution channel. The secondary distribution channelensures delivery and equalization of suction about the eye ring forsecure attachment to the eye.

[0028] Also according to aspects of the invention herein, the cuttinginstrument includes a cutter head having a blade assembly. The bladeassembly includes a metal cutting blade mounted to and extending from ablade holder to a cutting edge. The blade holder is preferablyfabricated of a polymer, such as nylon. The blade holder defines a drivetrack transverse to the cutter blade and its cutting edge. The cutterhead further defines a blade cavity generally accommodating andsupporting the blade holder for reciprocal sliding movement. The cutterhead defines a blade slot accommodating the cutting blade and extendingto a blade opening from a foot of the cutter head, adjacent which thecutting edge is deployed for incising the cornea. The cutting blade issuspended with respect to and does not contact the cutter head. Thecutter head defining the blade cavity is preferably of unitary,one-piece construction, but may also be comprised of a base and a captogether defining the blade cavity.

[0029] The blade cavity includes a guide bar cooperating with a guideslot formed in the blade holder. According to one aspect of theinvention, the guide is a linear guide bar received in the guide grooveformed in the blade holder, and configured for thin line contact betweenthe guide bar and the guide groove. According to another aspect of theinvention, the guide bar is comprised of two spaced apart postprojections received in the guide slot, which is parallel to the cuttingedge of the blade.

[0030] According to additional aspects of the invention, the bladecavity defines one of a guide slot or guide bar, and the blade holderdefines the other of the guide slot or guide bar, the guide barextending into the guide slot in closely conforming mating slidingengagement to guide and stabilize the blade holder in its reciprocalmovement within the cutter head. In a more particular aspect of theinvention, the cutter head defines a substantially rectangular guidebar, and the blade holder defines a substantially rectangular guide slotaccommodating the guide bar. The guide slot has an incrementally smallerwidth than the guide bar to preload the blade holder on the guide bar.The guide bar, and additional surfaces of the blade cavity, may betreated with a lubricous coating such as a nickel/Teflon® coating, toprovide smooth reciprocation.

[0031] The cutter head further includes a blade shield and foot, thefoot having projecting tongues for slidingly engaging the guide groovesof the shoe portion of the suction ring. The cutter head ischaracterized in that it does not contact the cutting blade, which issuspended extending from the blade holder. The cutting edge of the bladeextends a selected distance below a forward or toe surface of the footto establish a uniform depth of cut.

[0032] According to one aspect of the invention, the cutter headincludes a view port as part of the foot, for visually monitoringpassage of the cutter head and blade over the cornea and the cut.

[0033] In some aspects, the cutting instrument further includes a handledrive, to which the cutter head is secured. The handle drive has a driveshaft extending through the cutter head and terminating in an eccentricdrive pin received in the drive track of the blade holder. A handledrive turbine is used to rotate the drive shaft at high rpm, whichaccording to one aspect of the invention is between 8,000 and 16,000rpm, and thereby reciprocate the blade holder and blade. The drive shaftis supported on bearings and located to isolate application of the driveforce to the blade holder through the drive pin, in cooperation with thecutter head.

[0034] According to further aspects, the cutting instrument isreciprocally mounted in an automated drive unit. The automated driveunit is engageable with the suction ring, and the automated drive unithas drive means for advancing the cutting instrument and its cutter headacross the suction ring and for retracting the cutting instrument andcutter head after incising a cornea segment of an eye. The automateddrive unit is removably secured to the suction ring and can beintroduced in the suction ring after the suction ring is secured on theeye. Thus, the suction ring is attached without the bulk of theautomated drive unit and its cutting instrument, and the automated driveunit and associated cutting instrument and cutter head are easily joinedto the suction ring for cutting.

[0035] Also, according to aspects, the automated drive unit has athreaded shaft and worm gear and includes a motor powering the threadedshaft to translate the cutting instrument and cutter head. The motor maybe an electric motor, and an electrical spike at the limit of travel maybe used to reverse the direction of the cutting instrument and cutterhead for automated withdrawal. The cutting instrument may be inactivatedduring withdrawal.

[0036] According to other aspects, the cutting instrument includes atubular body with a motor and a cutter head, and the cutter head mountsto the tubular body by means of a mounting shank and a bayonet shapedgroove which positively orients the cutter head with respect to thetubular body. The bayonet style groove also provides for quick mountingand dismounting of the cutter head. According to additional aspects ofthe invention, the motor of the cutting instrument is connected to adrive shaft for reciprocating a cutter blade in the cutter head, theconnection being achieved by a coupling including a drive couplingmember having ears received in mating slots of a positioning couplingmember, and a positioning coupling member having pointed ears forguiding the drive ears into the mating slots.

[0037] According to further aspects of the invention, the keratome isprovided with a blade insertion tool which includes a shaft retractorfor retracting the drive pin of a blade drive shaft from the cutter headblade cavity to provide clearance for inserting the blade, and aninjector for inserting a cutter blade into the blade cavity and fordisplacing a used cutter blade out of the blade cavity.

[0038] Other objects, aspects and features of the invention will in partbe understood by those skilled in the art and will in part appear from aperusal of the following description of the preferred embodiments andthe claims, taken together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039]FIG. 1 is a perspective view of a keratome according to theinvention herein, including a suction ring and a cutting instrumenthaving a cutter head and handle drive;

[0040]FIG. 2 is a bottom perspective view of the keratome of FIG. 1;

[0041]FIG. 3 is a side elevation view of the keratome of FIG. 1;

[0042]FIG. 4 is a side elevation schematic view, partially in section,of the keratome of FIG. 1, shown incising a corneal segment;

[0043]FIG. 5 is a bottom perspective view of the suction ring of thekeratome of FIG. 1;

[0044]FIG. 6 is a top perspective view of the suction ring of thekeratome of FIG. 1;

[0045]FIG. 7 is a side elevation view, partially in section, of thesuction ring of the keratome of FIG. 1;

[0046]FIG. 8 is a perspective view of the suction ring of the keratomeof FIG. 1, and a schematic view of apparatus for applying suction to thesuction ring;

[0047]FIG. 9 is a longitudinal view, partially in section, of thecutting instrument of the keratome of FIG. 1;

[0048]FIG. 10 is a perspective view of the cutter head body of thecutting instrument of FIG. 9;

[0049]FIG. 11 is a perspective view of a cutting blade of a bladeassembly of the cutting instrument of FIG. 9;

[0050]FIG. 12 is a perspective view of a blade holder of a bladeassembly of the cutting instrument of FIG. 9;

[0051]FIG. 13 is a segmental side elevation view of the cutter head,showing an interface of the blade holder of FIG. 12 and cutter head bodyof FIG. 10;

[0052]FIG. 14 is an enlarged segmental view of the cutting instrument ofFIG. 9, showing the depth of cut of the blade;

[0053]FIG. 15 is an enlarged segmental view of a modified cuttinginstrument similar to FIG. 9, providing another depth of cut;

[0054]FIG. 16 is an enlarged segmental view of a modified cuttinginstrument similar to FIG. 9, providing another depth of cut;

[0055]FIG. 17 is a side elevation view of an additional cuttinginstrument of a keratome according to the invention herein,incorporating a cutter head with a two-piece body;

[0056]FIG. 18 is a perspective view of a suction ring and applanator ofanother keratome according to the invention herein;

[0057]FIG. 19 is a top view of the suction ring of FIG. 18;

[0058]FIG. 20 is a bottom view of the suction ring of FIG. 18;

[0059]FIG. 21 is an end view of the suction ring of FIG. 18;

[0060]FIG. 22 is a perspective view of the cutting instrument andsuction ring of the keratome of FIG. 18;

[0061]FIG. 23 is a side elevation view, partially in section, of thecutting instrument and suction ring of FIG. 22;

[0062]FIG. 24 is a perspective view of an adjustment collar for thecutting instrument of FIG. 22;

[0063]FIG. 25 is a side elevation view of the cutter head of the cuttinginstrument of FIG. 22;

[0064]FIG. 26 is a perspective view of the suction ring and applanatorof FIG. 18;

[0065]FIG. 27 is a perspective view of a blade holder of the cuttinginstrument of FIG. 22;

[0066]FIG. 28 is a side elevation view, partially in section, of thecutting instrument and suction ring of FIG. 22 in their stoppedposition;

[0067]FIG. 29 is a side elevation view, partially in section, of thesuction ring and applanator of FIG. 18;

[0068]FIG. 30 is a side elevation view of another keratome according tothe invention herein;

[0069]FIG. 31 is a perspective view of the keratome of FIG. 30,partially cut away;

[0070]FIG. 32 is an enlarged sectional view of the cutter head enteringthe suction ring of the keratome of FIG. 30;

[0071]FIG. 33 is an enlarged, partially sectional view of the cutterhead and automated drive unit engaged with the suction ring of thekeratome of FIG. 30;

[0072]FIG. 34 is a perspective view of a portion of the keratome of FIG.30, showing the cutter head and automated drive unit engaged with thesuction ring;

[0073]FIG. 35 is a perspective view a portion of the keratome of FIG.30, similar to the view of FIG. 34 and additionally cut away;

[0074]FIG. 36 is side elevation view, partially cut away, of the cuttinginstrument component of the keratome of FIG. 30;

[0075]FIG. 37 is a sectional view of the keratome of FIG. 30, takenalong the lines 37-37 of FIG. 31;

[0076]FIG. 38 is a foreshortened perspective view, partially cut away,of the keratome of FIG. 30;

[0077]FIG. 39 is a perspective view toward the bottom of the cutter headof the keratome of FIG. 30, illustrating its mounting shankconfiguration;

[0078]FIG. 40 is an enlarged view of the coupling between the cutterhead drive shaft and the motor drive of the cutting instrument of thekeratome of FIG. 30;

[0079]FIG. 41 is a perspective view of one of the positioning couplingelement of FIG. 40;

[0080]FIG. 42 is a perspective view of the drive coupling element ofFIG. 40;

[0081]FIG. 43 is a perspective view of the cutter head drive shaft ofthe keratome of FIG. 30;

[0082]FIG. 44 is a perspective view of the cutter head of the keratomeof FIG. 30, and one element of a blade insertion tool;

[0083]FIG. 45 is a perspective view of the cutter head and the elementof the blade insertion tool of FIG. 44 shown inserted in the cutterhead, and a second element of the blade insertion tool inserting acutter blade assembly; and

[0084]FIG. 46 is a perspective view of the cutter head, and first andsecond elements of the blade insertion tools shown removing a cutterblade from the cutter head.

[0085] The same reference numbers refer to the same elements throughoutthe various figures.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0086] With reference to FIGS. 1-13, there is illustrated a keratome 10according to the invention herein that is used in ophthalmic surgery forremoving a cornea segment. The keratome 10 generally comprises a suctionring 12 and a cutting instrument 14, which in turn generally comprises acutter head 16 and a handle drive 18. Various views of the keratome 10are illustrated in FIGS. 1, 2 and 3, and FIG. 4 illustrates the keratome10 removing a cornea segment 20 from the cornea 22 of an eye 24. Beforediscussing the keratome 10 and its operation in detail, the variouscomponent parts will be individually described.

[0087] FIGS. 5-7 depict various views of the suction ring 12. Thesuction ring 12 includes an eye ring 26 having a generally L-shapedcross-section as best seen in FIG. 7. The eye ring 26 defines a corneaaperture 28 and defines a first annular inner eye contact surface 30adjacent the cornea aperture 28. The eye ring 26 further defines asecond, annular outer eye contact surface 32 which is spaced apart fromthe first inner contact surface 30, with a suction channel 34 definedtherebetween. As best seen in FIG. 4, the contact surfaces 30 and 32engage with the exterior of the eye, wherein the surface of the eye alsodefines the suction channel 34. The contact surfaces 30 and 32 areangled and curved to conform to the contour of the eye, thereby insuringgood engagement with and sealing to the eye.

[0088] The suction ring 12 further comprises a conduit stem 36 having aconduit opening 38 for providing suction to the suction channel 34. Theconduit stem is mounted through the eye ring 26 so that the conduitopening 38 communicates with the suction channel 34. In some instances,the eye could be deformed to block the opening 38 or the suction channel34, and if this occurs the suction is weakened and the suction ring maydisengage or slip relative to the eye. To prevent this, the eye ring 26further defines a secondary distribution channel 40 extending inwardlyfrom the suction channel 34 and intersecting the conduit opening 38. Thedistribution channel 40 is sufficiently deep and narrow at its openingthat the eye cannot block it, and it assures that equal suction isprovided around the entire periphery of the eye ring.

[0089] The suction ring also defines a shoe 42 from which the eye ringdepends. The shoe 42 is configured for receiving the cutter head 16, theshoe 42 comprising the flat surface 43 flanked by two guide grooves 44and 45, the entrances to which are flared outwardly.

[0090] With reference to FIG. 8, a pump 46 develops negative pressure,also referred to as suction, through a conduit 47 having an accumulator48 therein. A valve 49 controls application of the suction to thesuction ring 12, and a gauge 50 provides an indication of the suction.The valve 49 may include provision for foot pedal operation, if desired.A filter 51 is also preferably provided. The conduit 47 is attached tothe conduit stem 36 of the suction ring 12, to apply the suction to thesuction channel 34 and secondary distribution channel 40.

[0091] It will be appreciated that the eye ring 26 is applied to the eyewith the cornea positioned in the cornea aperture 28 and is secured tothe eye by application of suction. The suction ring 12 provides a fixedbase for applying the cutting instrument 14, which is received on theshoe 42, as more fully discussed below.

[0092] With reference to FIGS. 9-14, the cutting instrument 14 of thekeratome 10 includes the cutter head 16 and handle drive 18. The cutterhead 16 includes a body 54, shown in FIG. 10, and a blade assembly 56,with a blade 58 and a blade holder 60 of the blade assembly 56 beingshown in FIGS. 11 and 12, respectively. The blade holder 60 is a shapednylon body having a mounting stud 62 extending from the bottom thereof,and the blade 58 has an opening 64 which is received surrounding themounting stud 62 to mount the blade on the blade holder, with the bladeextending therefrom to a cutting edge 72. The blade holder 60 defines aguide slot 68 which extends across the back surface 66, parallel to theblade 58 and its cutting edge 72, and the back surface 66 furtherdefines a drive track 70, perpendicular to the guide slot 68. Thecutting edge 72 of the blade extends oppositely from the back surface 66of the blade holder as seen for instance in FIGS. 3, 4 and 9.

[0093] The body 54 of the cutter head 16 is a one-piece, unitarystructure defining a blade holder cavity 74 which closely embraces andguides the blade holder 60, but permits the blade 58 suspended fromblade holder 60 to operate free from contact with the cutter head body54. More particularly, the cutter head includes a guide bar 76 which isreceived in the guide slot 68 in the back surface 66 of the blade holder60, and the top of the blade holder and front surface of the bladeholder also are slidingly engaged within the blade holder cavity 74.With particular reference to FIG. 13, the guide bar 76 and the groove 68are shaped so that there is contact 67 and 69 at the corners of theguide bar 76 and guide slot 68, which provide for guiding the bladeholder in transverse reciprocating motion with a minimum of binding,friction or blade flutter.

[0094] As best seen in FIG. 9, the cutter head 16 further comprisesprecision bearings 94, which receive a drive shaft 90 extending from thehandle drive 18 and having a drive pin 92 eccentrically located on theend thereof. The drive pin 92 extends into the drive track 70, so thatwhen the drive shaft 90 is rotated, the drive pin 92 reciprocates theblade assembly 56. The drive shaft 90 is supported on precision bearings94 which limit the extension of the drive shaft and drive pin into theblade cavity 74 in order to prevent the end of the drive shaft fromcontacting the blade holder and creating friction and binding.

[0095] The body 54 of the cutter head 16 further defines a blade slot 78extending from the blade holder cavity 74, in which the blade 58 issuspended by the blade holder without touching the body 54. A bladeshield portion 75 of the body 54 is located above the suspended blade.

[0096] The body 54 further defines a foot 80 having a blade opening 86,through which the cutting edge 72 of the blade 58 protrudes, as bestseen in FIGS. 2, 4, and 14. The foot 80 includes a toe portion 81 havinga first sole surface 82 and heel portion 83 with a second sole surface84, separated from the first sole surface 82 by blade opening 86. Theblade opening 86 is formed where the blade slot 78 intersects the sole.The sole surfaces 82 and 84 are flanked by projecting tongues 88 and 89which are respectively received in the guide grooves 44 and 45 of thesuction ring 12. Thus, the cutter head 16 is engageable with the shoe 42of suction ring 12 to pass the cutting edge 72 of cutter blade 58 acrossthe cornea, as best seen in FIGS. 1-4. It will be appreciated that thecutter head 16 may pass in either direction on the suction ring 12, andthat the suction ring may be engaged with either eye, as required toachieve clearance from the nose.

[0097] The blade assembly 56 is inserted in and removed from the cutterhead by first disengaging the drive pin, and then sliding the bladeassembly in and out of the blade holder cavity 74.

[0098] With reference to FIGS. 4 and 14, the first sole surface 82 ofthe cutter head 16 is stepped upwardly from the second sole surface 84,and the blade 58 extends through the blade opening 86 so that itscutting edge 72 is below sole surface 82. When the suction ring 12 isattached, the cornea extends upwardly through the cornea aperture 28 andis pressed against the sole surfaces of the cutter head as the cutterhead passes over the cornea aperture. The cornea is thereby cut to adepth D determined by the extension of the cutting edge 72 of cutterblade 58 below sole surface 82. The lower, second sole surface 84 alsosupports the cornea, including the truncated surface thereof, andassists in presenting and stabilizing the cornea with respect to theblade edge 76 for cutting.

[0099] With reference to FIGS. 15 and 16, portions of modified cutterheads 16a and 16b are shown in enlarged segmental section similar toFIG. 14. Cutter heads 16 a and 16 b are respectively provided withcutting blades 58 a and 58 b being respectively longer and intermediatethe blade 58 shown in FIG. 14, so that their cutting edges 72 a and 72 bprovide for deeper cuts D1 and D2 incising thicker cornea segments, asdictated by the requirements of a particular eye and procedure. Thetrailing sole surfaces 84 a and 84 b are also preferably lowered tocooperate respectively with the longer blades in providing a deeper cut.Although it is preferred to utilize a modified head to provide a deepercut, it will be appreciated that one of the longer blades 58 a or 58 bcan be used with cutter head 16 to provide a deeper cut than the blade58.

[0100] With reference to FIG. 9, the cutter head 16 is supported on andthe blade assembly 56 is reciprocally driven by the handle drive 18. Thehandle drive 18 includes a generally tubular body 100 which is securedto a mounting shank 98 of the cutter head 16 by cooperating matingquadralead threads 102. A flared collar 103 is positioned adjacent thecutter head, providing a comfortable control grip and also functioningas a stop, as further discussed below. The handle drive 18 also has adrive shaft 104 supported on bearings 106 and axially slidably coupledat 108 with respect to the drive shaft 90.

[0101] The handle drive further includes a turbine 110 which is drivenby compressed air, which may be supplied by pump 46, and rotates thedrive shafts 104 and 90 at approximately 8,000 to 16,000 rpms.Therefore, the cutter blade 58 makes full reciprocal cycles at the samefrequency.

[0102] With reference to FIG. 4, operation of the keratome 10 isillustrated. The suction ring 12 is positioned and engaged on eye 24 asdescribed above, and the foot 80 of the cutter head 16 is engaged withthe shoe of the suction ring by sliding tongues 88, 89 into guidegrooves 44, 45. By advancing the cutter head 16 across the suction ring,the cornea is presented to the cutting edge 72 of blade 58. The corneaengages the forward sole surface 82, on the toe 81 of the foot of thecutter head, prior to presentation to the cutting edge 72. Because theedge 72 of the cutting blade is disposed below the sole surface 82 by afixed depth D, the edge of the cutting blade thereby engages and incisesa cornea segment 20. The blade shield portion 75 of the cutter head 16lifts the cornea segment 20 and separates it so that a smooth cut mayproceed. The rear or heel sole surface 84 supports the truncated portionof the cornea as indicated at 120, also stabilizing the cornea as thecut proceeds. The toe may include a transparent insert so that theprogress of the cutter head across the cornea may be seen. The extent ofthe incision is limited by the abutment of flared collar 103 againstsuction ring 12, which occurs generally at 112, providing for a hingeportion of the cornea connecting cornea segment 20 to the cornea 22.

[0103] The cutting blade is disposed at an angle of approximatelytwenty-five degrees (25° ) with respect to the sole surfaces of thecutter head, and it has been found that this angle produces a smooth andaccurate cut. The angle, however, is not believed to be critical.

[0104] With continued reference to FIG. 4, the cutting blade 58 does nottouch the body 54 of the cutter head, but is positioned by the bladeholder 60 in a suspended relationship to the surrounding structure.Therefore, there is no friction and wear generated between the cuttingblade 58 and the cutter head body 54, and no debris is created whichwould contaminate the incision.

[0105] The handle drive 18 extends rearwardly from the cutter head 16 insubstantially parallel relationship to the direction of the motion ofthe cutter in performing an incision, and it has been found that this isa comfortable and controllable orientation of the handle for thesurgeon. Upon completion of the cut, the cutting instrument 10 iswithdrawn from the suction ring 12 and the suction ring 12 may then bereleased from the eye in accordance with further aspects of the surgicalprocedure.

[0106] With reference to FIG. 17, an alternative cutting instrument 150with a cutter head 151 according to the invention herein is illustrated.The cutter head 151 is characterized by a two-piece construction,including a base 152 and a cap 154. The base 152 and cap 154 togetherdefine a blade cavity 156 receiving blade assembly 56, including theblade 58 and blade holder 60. The base 152 provides the foot of thecutter head and extends upwardly to mount bearings 158 for drive shaft90, including drive pin 92, extending from cooperating handle drive 18,not otherwise shown. The base includes the lower half 161 of mountingshank 160, partially surrounding drive shaft 90.

[0107] The cap 154 includes the upper half 162 of mounting shank 160,and is secured to the base 152, when the handle drive 18 is threadedinto the mounting shank surrounding the upper and lower mounting shankportions and holding them together. The cap 154 also partially definesthe blade cavity 156. The cap 154 mounts a pair of spaced, roundedguides 168, which are the guide bars for this embodiment and arereceived in the guide slot 68 of the blade assembly 56, for guiding theblade assembly in its reciprocal motion. Springs 170 bias the guides 168into guide slot 68.

[0108] In this embodiment, the cap is removed from the base to insertthe blade assembly, and the cutter head is then secured to the cuttinginstrument by attaching the handle drive 18, and thereby alsointroducing the drive pin 92 to the drive track on the rear of the bladeassembly.

[0109] The cutter head 151 also includes a toe 171 with a transparentportion 172 for viewing the cornea. This feature is equally applicableto cutter head 16 described above.

[0110] Another keratome 200 according to the invention herein isillustrated in FIGS. 18-29. The keratome 200 generally comprises asuction ring 202, and a cutting instrument 204. An applanator 205cooperates with the suction ring 202 prior to incising a cornea section.

[0111] The cutting instrument 204 has a cutter head 206 which is thesame as cutter head 16 described above, except for the shape of theblade cavity 210 and blade holder 212, which will be discussed in moredetail below. Other parts of the cutter head 206 correspond to the sameparts of cutter head 16, and are given the same reference numerals inthe drawings and discussion of keratome 200.

[0112] The cutting instrument 204 also includes a handle drive 218,which is similar in its internal structure to the handle drive 18 ofkeratome 10 described above. The handle drive 218 is distinguished by atubular body 220 that is elongated with respect to the tubular body 100of handle drive 18, the elongated tubular body extending between thecutter head 206 and an adjustable stop ring 222 surrounding the tubularbody 220 adjacent flared collar 103. The drive shaft of the handle drive218 is, of course, also elongated to provide drive pin 92 extending intothe blade cavity 210, again as more fully described below.

[0113] The suction ring 202 is shown in FIGS. 18-21, as well as in otherfigures in combination with other elements of the keratome 200. Thesuction ring 202 includes an eye ring 26, which is the same as the eyering 26 described above in connection with suction ring 12. Withparticular reference to FIG. 20, the eye ring 26 has an inner annularcontact surface 30 adjacent a cornea aperture 28, and an outer annularcontact surface 32. A suction channel 34 is defined between the innerand outer contact surfaces 30, 32, and a secondary distribution channel40 extends around the suction channel 34 and intersects with conduitstem opening 38. The suction ring is provided with a conduit stem 224for connection with the source of negative pressure, such as shown inFIG. 8 and described above. The conduit stem is not shown in all of thefigures for clarity of the remaining parts.

[0114] The suction ring 202 has a shoe 230 including a planer bottomwall 232 from which the eye ring 26 depends and which also defines thecornea aperture 28. The shoe 230 has side walls 234 and 236 upstandingfrom the bottom wall 232, and the side walls 234 and 236 merge with aguide hoop 240 at an entrance end of the suction ring 202 and with ahandle 242 at the handle end of the suction ring 202.

[0115] The suction ring 202 cooperates with an applanator 205 inmeasuring the cornea segment 20 prior to incising thereof. Theapplanator 205 has a generally tubular barrel portion 244 and a handleportion 246, which are integrally fabricated of an optically clearmaterial, such as Lexan®. The applanator has a measuring surface 248which is recessed below the end 249 of barrel 244. The depth of recessis preferably the same height that the cutting edge 72 of the cuttingblade 58 is disposed above the bottom wall 232 as the cutter head 206 isemployed to incise the cornea. The measurement surface 248 is providedwith a plurality of concentric rings 250 which are used in measuring thesize of the cornea segment. In the embodiment shown, the inner ring is8.5 millimeters in diameter, the central ring is 9.0 millimeters indiameter and the outside ring is 9.5 millimeters in diameter. Theapplanator is flattened at 252 for clearance with respect to the suctionring.

[0116] The side walls 234 and 236 of the suction ring define opposedcurved socket portions 255 and 256 of a socket 254, which positions thebarrel 244 of the applanator 205 centrally over the cornea aperture 28,as seen in FIGS. 26 and 28. The flats 252 of the applanator accommodateportions of the side walls which define guideways for the cutter head206, as more fully discussed below.

[0117] As best seen in FIG. 29, when the suction ring 202 is secured toeye 24, the cornea 22 protrudes through the cornea aperture 28 andextends above the bottom wall 232. When the applanator 205 is receivedin the socket defined by the curved socket portions 254 and 256 of thesuction ring side walls, and is also supported with its end 249 on thebottom wall 232, the cornea is in contact with the measuring surface 248of the applanator. The surgeon views the concentric rings and corneacontact portion axially through the applanator 205. The diameter of thecontact portion of the cornea is ascertained by reference to theconcentric rings 250 on the measurement surface, and corresponds to thesize of the cornea segment 20 which will be incised by the cuttinginstrument 204. Upon ascertaining the size of the cornea segment, theapplanator is removed from the socket 254.

[0118] The keratome 200 is characterized by accurate engagement betweenthe cutting instrument 204 and the suction ring 202, and by easyinsertion of the cutting instrument into the suction ring. To this end,the shoe 230 of the suction ring defines a cutting guideway 260configured for receiving the cutter head 206 in precision mating slidingengagement. Adjacent the precision cutting guideway 260 and extending tothe entrance end 262 of the suction ring is an entrance guideway 264,with the guide hoop 240 providing transition between the entranceguideway 264 and the cutting guideway 260.

[0119] The cutting guideway 260 includes precision guide grooves 266 and267 respectively at the intersections of the bottom wall 232 andsidewalls 234, 236. The guide grooves 266, 267 respectively slidinglyreceive the tongues 88 and 89 of the cutter head 206. The precisionguide grooves 266 and 267 are fully defined only in the cutting guideway260 and the entrance guideway 264 serves to position the cutter head 206for accurately and easily engaging the tongues 88 and 89 in theprecision guide grooves 266 and 267.

[0120] The entrance guideway 264 begins with an entrance ramp portion270 of the bottom wall 232, the entrance ramp portion 270 being providedwith curbs 272 and 274 at its marginal edges. The lower portions ofguide grooves 266, 267 are partially defined adjacent the curbs 272,274, such that the tongues 88, 89 can drop into the partially definedguide grooves; however, this does not require precision alignment and ismerely part of the function of the entrance guideway 264 in orientingand positioning the cutter head with respect to the cutting guideway. Atthe entrance to the guide hoop 240, the side wall 236 defines a toe slot276 and a toe slot ramp 278. The toe slot ramp 278 is positioned under aside rail 280 which extends inwardly from the toe slot ramp 278 and theinterior of the guide hoop 240. The side wall 234 similarly defines toeslot 277, a toe slot ramp 279 and a side rail 281. The side rails 280and 281 are discontinuous at the socket walls 255 and 256 as are the toeslot ramps 278 and 279.

[0121]FIGS. 22 and 23 illustrate entry of the cutting instrument 204into the suction ring 202. Although the user's hands are not shown, itwill be appreciated that the user will hold the handle 242 in one handand will manipulate the cutting instrument 204 with the other hand. Itis advantageous to have both hands involved in the insertion of thecutting instrument 204 into the suction ring 202, in that the user canstabilize the suction ring 202 on the eye by sensing and compensatingfor any insertion forces, and also because the use of two hands tends toachieve better spacial orientation and physical coordination in makingthe insertion.

[0122] The toe 81 of the cutter head 206, including the leading portionsof tongues 88 and 89, are placed against the entrance ramp portion 270of the shoe 230. If the tongues 88 and 89 are placed between the curbs272 and 274, the toe is guided along bottom wall 232 into the guide hoop240, and the tongues then enter the fully defined guide grooves 266 and267. If the tubular body 220 and cutter head 206 of the cuttinginstrument 204 are not axially oriented with respect to the cuttingguideway 260, a curved forehead 284 or one of flanking edges 286 and 287defining the outer edges of the forehead 284 engages the guide hoop 240and directs the cutting instrument 204 toward alignment. This engagementand continued forward movement of the cutting instrument 204 intoentrance guideway 264 causes the tubular body 220 and cutter head 206 tobe axially aligned with the cutting guideway 260, and permits thetongues 88, 89 to enter the guide grooves 266 and 267, as seen in FIG.23.

[0123] If the toe 81 of cutter head 206 is somewhat tilted or initiallymisaligned, it will contact one of the toe slots 276, 277, or one of thetoe slot ramps 278, 279, which will direct the toe into an adjacentrespective toe slot. This provides an initial near alignment which isfurther corrected into axial alignment by contact of the forehead 284 orthe transition edges 286 and 287 with the guide hoop 240, ultimatelyresulting in axially alignment of the cutting instrument 204 with thecutting guideway, and engagement of the tongues 88, 89 in the precisionguide grooves 266, 267.

[0124] In all instances in which the toe 81 is inserted into theentrance guideway with the toe positioned under the side rails 280 and281, the entrance guideway will accept the toe and by contact with theforehead 284 and transition edges 286, 287 the remainder of the cutterhead will achieve alignment of the cutting instrument 204 for entry intothe cutting guideway 260. It will be appreciated that the entranceguideway 264 tolerates misalignment on initial insertion and correctsthe alignment as insertion into the entrance guideway 264 proceeds,making it extremely easy for the user to achieve the correct alignmentof the cutting instrument 204 on the suction ring 202. The entranceguideway 264 has the additional benefit of providing entry to thesuction ring 202 in an area spaced apart from the cornea aperture 28,thereby also preventing accidental damage to the cornea as a result ofmis-engagement between the cutting instrument 204 and suction ring 202.

[0125] It will be noted that the cutter head 206 defines elongated siderail pockets 282 and 283 spaced upwardly from and parallel to thetongues 88, 89, and these pockets are matingly shaped with and slidinglythe side rails 280, 281 of the suction ring 202. The diameter of thetubular body 220 is preferably selected so that it substantially matchesthe interior of the guide hoop 240, including the upper portions of theside rails 280 and 281, so that the cutter head 206 and tubular body 220are slidingly accommodated in the guide hoop 240.

[0126] As the cutting instrument enters the cutting guideway 260, thetongues 88 and 89 are received in the precision grooves 266, 267, theside rails 280, 281 are received in the rail pockets 282, 283. As thecutting instrument progresses within the cutting guideway 260, thetubular body 220 is received in the guide hoop 240. Thus, the cuttinginstrument is fully supported and precisely positioned on the suctionring 202 as the cutting blade moves across the cornea aperture 28, asbest seen in FIG. 28.

[0127] As also best seen in FIG. 28, before the cutting edge 72 of thecutting blade 58 moves completely across the cornea aperture, the stopring 222 engages the guide hoop 240, limiting further insertion movementof the cutting instrument 204 and thereby preserving a hinge between anincised cornea section and the cornea. With particular reference toFIGS. 22, 24 and 28, the stop ring 222 has three stop surfaces 290, 292and 294, which are marked with indicia coordinating the stop surfaceswith the size of the cornea contact patch measured with the applanator205. The user selects the desired stop surface corresponding to themeasured size prior to inserting the cutting instrument 204 into thesuction ring 202, and the stop ring contacts the guide hoop at 289 whenthe cut has proceeded for the desired, selected distance.

[0128] The keratome 200 is also characterized by stabilizedreciprocating movement of the cutting edge 72 of blade 58, in order toachieve a very smooth incision of the cornea. With particular referenceto FIGS. 25 and 27, the cutter head 206 defines a guide bar 296, whichis substantially rectangular when viewed in side elevation. The bladeholder 212 is provided with a mating rectangular guide slot 214, whichreceives and closely embraces the guide bar 296. In the embodimentshown, the blade holder 212 is fabricated of nylon and has a width Wfrom the guide slot to the top is larger than the corresponding width W′from the guide bar to the top of the blade holder cavity byapproximately 0.0005-0010 inches. This provides a “preloaded” engagementof the blade holder on the guide bar and achieves a positive, supported,stabilized alignment of the blade holder on the guide bar duringreciprocating movement. The surface of the blade cavity is preferablycoated with a nickel/Teflon® material to provide smooth reciprocation,effectively lubricating the preloaded interface between the guide bar296 and the guide slot 214. Because the guide slot 214 is substantiallylarger and deeper than the guide slots on the blade holders of theprevious embodiments, it is placed lower on the blade holder so that itdoes not intersect the drive track 216, which receives the eccentricdrive pin 92 for reciprocating the blade holder 212. It should also benoted that the blade holder 212 may define a guide bar and the bladecavity define a guide slot, if desired. The blade 58 is secured tomounting stud 62 of the blade holder 212, and does not contact thecutter head 206.

[0129] Thus, the keratome 200 is used by first engaging the suction ring202 with the patient's eye and then using the applanator 205 to measurethe proposed cornea section. Stop ring 222 of the cutting instrument isset to the desired size, and the cutting instrument is inserted into theentrance guideway 264 of the suction ring. Engineered interferencebetween the cutting instrument and the suction ring causes alignmentwith and entry into the cutting guideway 260 of the suction ring. Thecutting guideway precisely positions the cutting blade as it incises thecornea. The cutting blade is reciprocated in making the cut, and thecutting blade is suspended with respect to contact with surroundingstructure of the cutting instrument, and is stabilized for a smooth cut.

[0130] Another keratome 300 according to the invention providesautomated reciprocal drive of a cutting instrument having a cutter head.With reference to FIGS. 30-46, as well as other Figures, the keratome300 generally comprises an automated drive unit 310, a suction ring 312and a cutting instrument 314 including a cutter head 330.

[0131] The cutting instrument 314, cutter head 330 and suction ring 312are all similar to the cutting instrument 204, cutter head 206 andsuction ring 202 of keratome 200 described above. However, the automateddrive unit 310 of keratome 300 engages with the suction ring 12 andprovides for automated translational movement of the cutter head 330across the cornea of an eye.

[0132] With reference to FIG. 30, the keratome 300 first comprisesautomated drive unit 310, having a main housing 316, a front transitionhousing 318, and a rear transition housing 320 terminating in a cablecap 322 from which the wires necessary to power the keratome extend. Thefront transition housing 318 is designed to engage with guide hoop 240of the suction ring 312 and, as seen in FIGS. 31 and 32, the suctionring 312 defines a notch 324 receiving tongue 325 of a pivotal latch 326of the front transition housing 318.

[0133] The cutting instrument 314 includes a cutter head 330, which issimilar to cutter head 206 described above. With reference to FIG. 36,the cutting instrument 314 defines a generally tubular body 332, andwith reference to FIGS. 31-35, the tubular body is guided for reciprocalmotion in the automated drive unit 310 by a bushing 334 at the front ofthe automated drive unit. The cutter head 330 is guided into the suctionring 312 in the manner discussed above with respect to cutter head 206and suction ring 202 and as shown in FIG. 32. With reference to FIG. 33,when the cutter head 330 has entered the guide hoop 240, the fronttransition housing 318 also receives and engages with the rear portionof the suction ring and the tongue 325 of latch 326 is received in notch324 to secure the automated drive unit 310 and cutter instrument 314 tothe suction ring 312. The suction ring is, of course, secured to an eyein performing a cornea incision.

[0134] The automated drive unit 310 reciprocally translates the cutterhead 330 of cutting instrument 314 on the suction ring 312. To this end,the cutting instrument 314 has a worm gear 340 extending from thetubular body 332 and the handle drive has a threaded shaft 342 (threadsnot shown) which is received in the worm gear 340. The threaded shaft342 is rotatably mounted in a front plate 344 of the reciprocal handledrive 310. The other end of shaft 342 is mounted to rear plate 345 andhas a gear 346, which meshes with a gear 348 of a drive motor 350, asbest seen in FIGS. 37 and 38. When the motor 350 spins gears 348 and346, the threaded shaft 342 translates the cutting instrument 314 intothe suction ring and across the eye opening thereof, to incise thecornea. When the worm gear 340 engages bushing 334, the load on themotor 350 is increased suddenly and dramatically, causing an electricalspike which is used as a control signal to reverse the direction of themotor 350 and withdraw the cutting instrument 314. The electrical spikemay also be used as a signal to stop operation of motor 352, whichreciprocates the cutting blade in the cutter head 330 of the cuttinginstrument. When the motor 350 moves the cutting instrument 314 backinto the reciprocal handle drive 310, a microswitch 354 is used to stopoperation of the motor 350 when the cutting instrument is fullyretracted. An electronics package 356 controls these operations, withexternal input via operating switches.

[0135] A coil spring 360 is mounted surrounding shaft 342 and provides abias load between the threaded shaft 342 and the worm gear 340, whichprevents any gear lash which might otherwise cause an unsmooth motion ofthe cutting instrument 314 in the suction ring 312.

[0136] With reference to FIGS. 31-36 and 39, the cutter head 330 has acylindrical mounting shank 362 defining a bayonet mounting slot 364. Thebayonet mounting slot cooperates with a pin 366 mounted to the tubularbody 32 of the cutting instrument. More particularly, the bayonetmounting slot 364 defines an entry way 368, and a retention end 370 inwhich the pin 366 seats to lock the cutter head into the desiredorientation on the tubular housing 332, and also provides for easyremoval of the cutter head 330 for sterilization, or blade changes.

[0137] The cutting instrument includes a coupling 374, best seen inFIGS. 36 and 40-43, connecting the motor 352 and a drive shaft 376extending through bearing block 372 into the cutter head 330 foroscillating a cutting blade, in the manner described above. The coupling374 includes a first, positioning coupling member 378 having positioningears 380 and 382, which are preferably pointed. The positioning couplingmember 378 also includes a central opening 384 in which the drive shaft376 is received with the end 377 thereof (FIG. 43) protruding throughthe coupling member 378. The coupling 374 further comprises the drivecoupling member 388, characterized by rounded ears 390 and 392 which fitsnugly in slots 389 and 391 of the positioning coupling member 378.Drive coupling member 388 also defines an axial opening 389, whichreceives the end 377 of drive shaft 376 when the coupling members areassembled together.

[0138] Therefore, when the cutter head 330 is removed from the remainderof the cutting instrument, the coupling members 378 and 388 separate,and when the cutter head is reattached, the drive ears 390 and 392 willeither immediately settle into the slots 389, 391 or will engage againstthe pointed ears 380, 382 and be directed in to the slots 389, 391. Asnoted above, the drive shaft protrudes through the positioning couplingmember 378 into opening 389 of the drive coupling member 388, for secureaxial alignment of the coupling 374.

[0139] The keratome 300 is also provided with an accessory bladeinsertion tool 400, shown in FIGS. 44-46, which operates with respect tothe cutter head after its removal from the cutting instrument, bydisengagement of the bayonet mount. The function of the blade insertiontool is to retract the drive shaft 376 in order to remove the drive pin402 of the drive shaft from the blade cavity 331 defined in the cutterhead 330, in order that a cutting blade assembly can be inserted withoutinterference with the drive pin. To this end, the cutter head 330 isprovided with an access slot 404 behind the blade holder cavity 331, theend 410 of the drive shaft is partially cut away with respect to thedrive pin and further defines a shoulder 412, and the drive shaft isaxially biased to position the drive pin in the blade cavity and providefor retraction from the blade holder cavity.

[0140] With reference to FIG. 44, the blade insertion tool 400 comprisesa shaft retractor and blade holder 414, including a tip 416 havingramped back surfaces 418 and 420 for engaging the shoulder 412 of thedrive shaft and pushing the drive shaft rearwardly. The tip 416 alsodefines a shaped slot 422 for receiving tip 410 of the drive shaft. Theshaft retractor and blade holder 414 also defines a shaped bladeassembly support surface, generally referred to at 424, for receivingand positioning a cutting blade 58 and blade holder 212 adjacent thecutter head 330, which is also supported on the shaft retractor andblade holder 414. FIG. 45 shows the shaft retractor with its tip 416inserted in the cutter head 330, and the blade holder 212 is adjacentblade holder cavity 331 and blade 58 adjacent the blade slot.

[0141] With continued reference to FIG. 45, the blade insertion tool 400further comprises an injector 428, which is received in groove 430 ofthe shaft retractor 414, and is slid therealong to push the blade 58 andblade holder 212 supported on the blade support surface 424 into theblade holder cavity 331 of the cutter head 330. The injector 428 has apivotally mounted stop member 432 which, when oriented toward the cutterhead 330 as shown in FIG. 45, abuts and stops against the cutter head330 when the blade holder is inserted centrally in the blade holdercavity 331. Therefore, on withdrawal of the shaft retractor 414 and itstip 416, the drive pin 402 moves forward into the drive track of theblade. It may be necessary to rotate the drive shaft to seat theeccentric drive pin, but the drive track is accurately positioned toreceive it.

[0142] When the stop member 432 is pivoted upwardly, as shown in FIG.46, the injector 428 may be slid into the blade cavity 331, displacingthe blade assembly therein and thus providing for removal of usedblades.

[0143] It will be appreciated that in FIGS. 45 and 46, the cutter head330 is shown disassociated from the other portions of the cuttinginstrument 314 and the automated drive unit 310, so that the drive shaftmay be retracted. The bayonet mount of the cutter head and the coupling374 facilitate easy removal and replacement of the cutter head and,together with the blade insertion tool, make it a simple matter tochange blade assemblies.

[0144] The keratomes described above achieves very smooth incisions ofthe cornea in releasing a cornea segment, and does not damage orcontaminate the cornea beyond the desired surgical incision.

[0145] Accordingly, keratomes have been described of which fulfill theobjects of the invention herein. It will be appreciated by those skilledin the art that the keratomes described above are illustrative of theinvention, but that various changes and adaptations can be made withoutdeparting from the spirit and scope of the invention, which is limitedonly by the following claims and structures which may fairly falltherebetween.

We claim:
 1. A keratome comprising: A) a cutter head having a body and ablade assembly, 1) the blade assembly including a blade holder having adrive track and one of a guide slot or a guide bar substantiallytransverse to the drive track, the blade assembly further including ablade mounted to and extending outwardly from the blade holder to acutting edge substantially parallel to the guide slot or guide bar, and2) the cutter head body defining a) a sole surface for slidingengagement with a cornea, the sole surface defining a blade opening, b)a blade holder cavity shaped to receive the blade holder inreciprocating movement, the blade holder cavity defining the other ofthe guide slot or guide bar, wherein the guide bar is received in theguide slot for stabilizing the blade holder in reciprocating motion inthe blade holder cavity, c) a blade slot extending between the bladeholder cavity and the blade opening, wherein the blade extends throughthe blade slot and blade opening with its cutting edge positioned belowthe sole surface, the blade slot and blade opening sized to accommodatethe blade without contact between the blade and the cutter head body,and d) a drive means access to the drive track of the blade holder.
 2. Ablade assembly for a keratome of the type including a cutter headdefining a blade holder cavity, one of a guide bar or guide slot, and adrive shaft opening to the blade cavity for receiving a drive shafthaving an eccentric revolving drive pin extending into the blade cavity,the blade assembly comprising: A) a blade holder configured forreciprocal sliding movement in the blade holder cavity of the cutterhead, the blade holder defining one of a guide slot or guide bar forengagement with the guide slot or guide bar of the cutter head, theblade holder further defining a drive track substantially perpendicularto the guide slot or guide bar for receiving the eccentric revolvingdrive pin; B) a blade mounted to the blade holder and extendingtherefrom to a blade edge substantially parallel to the guide slot orguide bar.
 3. A keratome comprising: A) a cutting instrument including acutter head having a reciprocating blade with a cutting edge extendingbelow a sole surface of the cutter head; B) a suction ring including aneye ring adapted to be secured to an eye by suction and defining acornea aperture for presenting the outer layer of the cornea of the eyefor cutting, and a shoe from which the eye ring extends, the shoedefining, a) a cutting guideway configured for receiving the cutter headin precision mating sliding engagement when the cutting edge of theblade is positioned over the cornea aperture of the eye ring, and b) anentrance guideway extending from and generally aligned with the cuttingguideway, the entrance guideway configured for receiving the cutter headin orienting sliding engagement and positively positioning the cutterhead for precision mating sliding engagement with the cutting guideway.4. A suction ring for positioning a cutter head having a cutting bladefor incising a cornea, the suction ring comprising: A) an eye ringhaving first and second generally concentric spaced apart surfaces sizedand shaped for engaging the eye on or adjacent the cornea thereof, theeye ring defining within the concentric spaced apart surfaces a corneaopening exposing a central portion of the cornea when the eye ring isengaged with the eye, the eye ring defining a suction channel betweenthe first and second concentric eye engaging surfaces, and a secondarydistribution channel extending inwardly from the suction channel, and B)a stem extending from the eye ring and having an opening forcommunicating suction with the eye ring, the stem opening intersectingthe suction channel and secondary distribution channel.
 5. An apparatusfor sizing an eye prior to incising the cornea of the eye and forcoordinating the corneal incision with eye size, comprising: A) asuction ring having an eye ring for engaging the eye on or adjacent tothe cornea, the eye ring defining a cornea aperture exposing a centralportion of the cornea; B) a shoe extending from the eye ring, the shoehaving a bottom wall surrounding the cornea aperture and an applanatorsocket extending upwardly from the bottom wall surrounding the corneaaperture; and C) an applanator removably received in the applanatorsocket, the applanator having a sizing surface which, when received inthe socket, is positioned adjacent to and above the cornea aperture,wherein a cornea presented in the cornea aperture extends to contact theapplanator sizing surface, and the applanator sizing surface includesindicia indicating the size of the contact between with the cornea andthe applanator sizing surface.
 6. A keratome comprising: A) a cuttinginstrument including a cutter head having a reciprocating blade with acutting edge extending below a sole surface of the cutter head; B) anautomated drive unit mounting the cutting instrument for poweredtranslational movement of at least the cutter head thereof; C) a suctionring including an eye ring adapted to be secured to an eye by suctionand defining a cornea aperture for presenting the outer layer of thecornea of the eye for cutting, and a shoe from which the eye ringextends, the shoe defining, 1) a cutting guideway configured forreceiving the cutter head in precision mating sliding engagement whenthe cutting edge of the blade is positioned over the cornea aperture ofthe eye ring, and 2) an entrance guideway extending from and generallyaligned with the cutting guideway, the entrance guideway configured forreceiving the cutter head in orienting sliding engagement and positivelypositioning the cutter head for precision mating sliding engagement withthe cutting guideway; D) said automated drive unit and said suction ringconfigured for releasable attachment when said cutter head is receivedin the entrance guideway of the suction ring, and E) said automateddrive unit operable to slidingly translate the cutter head into thecutting guideway and to withdraw the cutter head therefrom.
 7. Akeratome as defined in claim 6 wherein the cutter head has a body and ablade assembly, 1) the blade assembly including a blade holder having adrive track and one of a guide slot or a guide bar substantiallytransverse to the drive track, the blade assembly further including ablade mounted to and extending outwardly from the blade holder to acutting edge substantially parallel to the guide slot or guide bar, and2) the cutter head body defines a) a sole surface for sliding engagementwith a cornea, the sole surface defining a blade opening, b) a bladeholder cavity shaped to receive the blade holder in reciprocatingmovement, the blade holder cavity defining the other of the guide slotor guide bar, wherein the guide bar is received in the guide slot forstabilizing the blade holder in reciprocating movement in the bladeholder cavity, c) a blade slot extending between the blade holder cavityand the blade opening, wherein the blade extends through the blade slotand blade opening with its cutting edge positioned below the solesurface, the blade slot and blade opening sized to accommodate the bladewithout contact between the blade and the cutter head body.
 8. Akeratome as defined in claim 7 wherein the guide bar and guide slot havesubstantially rectangular mating configurations.
 9. A keratome asdefined in claim 8 wherein the guide slot has an incrementally smallerwidth than the guide bar, so that the guide bar is tightly received inthe guide slot.
 10. A keratome as defined in claim 9 wherein the guideslot is defined by the blade holder.
 11. A keratome as defined in claim7 wherein the guide slot is defined by the blade holder.
 12. A keratomeas defined in claim 7 wherein the cutter head is metal and the bladeholder is a plastic material.
 13. A keratome as defined in claim 12wherein the blade holder is nylon.
 14. a keratome as defined in claim 7wherein the eye ring has first and second generally concentric spacedapart surfaces sized and shaped for engaging the eye on or adjacent thecornea thereof, the eye ring defining within the concentric spaced apartsurfaces a cornea opening exposing a central portion of the cornea whenthe eye ring is engaged with the eye, the eye ring defining a suctionchannel between the first and second concentric eye engaging surfaces,and a secondary distribution channel extending inwardly from the suctionchannel, and a stem extending from the eye ring and having an openingfor communicating suction with the eye ring, the stem openingintersecting the suction channel and secondary distribution channel. 15.A keratome as defined in claim 6 wherein the suction ring has a guidehoop upstanding from the shoe thereof, the guide hoop receiving andsurrounding the cutter head as it enters the entrance guideway.
 16. Akeratome as defined in claim 15 wherein the cutter head and portion ofthe cutting instrument adjacent thereto are surrounded and embraced bythe hoop as the automated drive unit translates the cutter head into thecutting guideway.
 17. A keratome as defined in claim 15 wherein theguide hoop provides the transition between the entrance guideway and thecutting guideway.
 18. A keratome as defined in claim 15 wherein thecutter head has a toe and the shoe and guide hoop of the suction ringdefine flanking toe slots and toe ramps for guiding the toe of thecutter head into the entrance guideway.
 19. A keratome as defined inclaim 15 wherein the guide hop and cutter head are cooperativelyconfigured to guide the cutter head into the entrance guideway.
 20. Akeratome as defined in claim 19 wherein the cutter head includes guidetongues depending from the edges of its sole surface, and the suctionring defines guide grooves receiving the guide tongues as the automateddrive unit translates the cutter head in the cutting guideway.
 21. Akeratome as defined in claim 19 wherein the automated drive unit has ahousing surrounding the cutting instrument, and the housing is matinglyreceived and removably secured with the suction ring when the cutterhead is in the cutting guideway.
 22. A keratome as defined in claim 21wherein the guide hoop defines a notch and the housing of the automateddrive unit includes a latch removably engaged in the guide hoop notch.23. A keratome as defined in claim 15 wherein the automated drive unithas a housing surrounding the cutting instrument, and the housing ismatingly received and removably secured with the suction ring when thecutter head is in the cutting guideway.
 24. A keratome as defined inclaim 23 wherein the guide hoop defines a notch and the housing of theautomated drive unit includes a latch removably engaged in the guidehoop notch.
 25. A keratome as defined in claim 6 wherein the shoe fromwhich the eye ring extends has a bottom wall surrounding the corneaaperture and an applanator socket extending upwardly from the bottomwall surrounding the cornea aperture, and further comprising anapplanator removably received in the applanator socket, the applanatorhaving a sizing surface which, when received in the socket, ispositioned adjacent to and above the cornea aperture, wherein a corneapresented in the cornea aperture extends to contact the applanatorsizing surface, and the applanator sizing surface includes indiciaindicating the size of the contact between with the cornea and theapplanator sizing surface.
 26. A keratome as defined in claim 6 whereinthe automated drive unit has a housing surrounding the cuttinginstrument, and the housing is matingly received and removably securedwith the suction ring when the cutter head is in the cutting guideway.27. A keratome as defined in claim 6 wherein the automated drive unithas an elongated housing and the cutting instrument includes a generallytubular body slidingly mounted in the elongated housing for poweredextension and retraction with respect thereto to translate the cutterhead in the cutting guideway.
 28. A keratome as defined in claim 27wherein the cutting instrument has a motor that drives the reciprocatingblade in the cutter head by a drive shaft, and the automatic drive unithas an additional motor that translates the cutting instrument andcutting head.
 29. A keratome as defined in claim 28 wherein the tubularbody of the cutting instrument has a worm gear mounted thereon, and themotor of the automated drive unit turns a threaded shaft received in theworm gear to translate the cutting instrument and cutter head.
 30. Akeratome as defined in claim 29 wherein the motor of the automated driveunit is reversed at the desired extent of translation.
 31. A keratome asdefined in claim 30 wherein one of the cutting instruments or cutterhead is mechanically stopped at the desired extent of translation,thereby causing an electrical spike in the motor current used as acontrol signal to reverse the direction of translation.
 32. A keratomeas defined in claim 27 wherein the cutter head is removably secured tothe cutting instrument by a bayonet mount of a cutter head mountingshank.
 33. A keratome as defined in claim 32 wherein the drive shaft ofthe cutter head and a drive shaft of the cutting instrument motor areconnected by an axially engageable coupling that releases and engages asthe cutter head is removed and secured on the cutting instrument.
 34. Akeratome as defined in claim 33 wherein the coupling comprises a firstdrive coupling members having two ears flanking two slots, and a secondpositioning coupling having two slots receiving the two ears of thedrive coupling member and two substantially pointed ears guiding theengagement of the coupling.
 35. A blade insertion tool for a keratomecutter head defining a traverse blade holder cavity and blade slot forreceiving a blade assembly having a blade holder and blade, the cutterhead also having a retractable drive shaft with a drive pin extendinginto the blade holder cavity for engaging and driving the blade assemblyand defining a drive shaft access slot adjacent the blade holder cavity,the blade insertion tool comprising: A) a shaft retractor and bladeholder having 1) a shaft retractor top insertable in the drive shaftaccess slot and configured to engage and retract the drive shaft fromthe blade holder cavity, and 2) a blade assembly support surface which,when the shaft retractor tip is inserted in the drive shaft access slot,is positioned to support a blade assembly with its blade holder adjacentthe blade holder cavity and its blade adjacent the blade slot; and B) aninjector slidingly received on the shaft retractor and blade holder, theinjector configured to engage the cutter assembly and slide it into thecutter head positioned for engagement with the drive shaft uponwithdrawal of the shaft retractor tip.
 36. A blade insertion tool asdefined in claim 35 wherein the shaft retractor and blade holder is alsoconfigured to support the cutter head.
 37. The blade insertion tool asdefined in claim 35 wherein the injector defines a stop that buttsagainst the cutter head when the blade assembly is in the desiredposition with respect to the drive shaft.
 38. A blade insertion tool asdefined in claim 35 wherein the injector further comprises a stop memberpivotally mounted thereon for selection between 1) a first position inwhich the stop member butts against the cutter head when the bladeassembly is in the desired position with respect to the drive shaft, and2) a second position permitting the injector to enter the blade holdercavity and displace a blade assembly therefrom.